I have uploaded screenshots for community made maps and I would like to know why they were rejected? Is it because I uploaded the screenshots for custom maps, because they don't have a proper name or just because the screenshots were not "good" (eg. not showing enough of the map)?

If it's because the maps don't have a proper name, I would like to provide this list: https://pastebin.com/kTysmuwr
It contains most custom maps and their names.

It would be great if an admin could add these names to the maps.
But of course, only if you have the time and desire to do so.